Breast, Cervical, and Colorectal Cancer Screening Adherence: Effect of Low Body Mass Index in Women

Purpose: Health-related behaviors among underweight women have received less attention than overweight and obese women in the United States. Our purposes were to estimate the rate and modifiers of breast, cervical, and colorectal cancer screening adherence among underweight women and compare it to other body mass index (BMI) categories. Materials and Methods: We used sampling weighted data from 2016 Behavioral Risk Factor Surveillance System (BRFSS) of age-eligible women (breast cancer screening, n = 163,164; cervical, n = 113,883 and colorectal, n = 128,287). We defined breast, cervical, and colorectal cancer screening using the US Preventive Services Task Force (USPSTF) guidelines. We calculated the prevalence of screening among four BMI categories (underweight <18.5, normal weight ≥18.5 to <25, overweight ≥25 to <30, and obese ≥30). Logistic regression models assessed the independent effect of BMI on screening adherence. Results: Underweight women had significantly lower breast (62.9%), cervical (67.5%), and colorectal (62.6%) cancer screening rates compared to other BMI categories. In logistic regression models, being underweight was associated with decreased odds of breast (odds ratio [OR] = 0.66; 95% confidence interval [CI] = 0.49-0.88) and cervical (OR = 0.54, 95% CI = 0.34-0.84), but not colorectal (OR = 0.88; 95% CI = 0.66-1.18) cancer screening adherence. We did not demonstrate a significant association between obesity and screening rates for any of the three cancers. Underweight women reported higher rates of smoking and lower levels of educational attainment, income, and insurance coverage compared to all other groups. Higher rates of chronic illness and health access hardship were observed among underweight women. Conclusion: BMI variably affects cancer screening. Compared to normal-weight women, being underweight is associated with breast and cervical cancer screening nonadherence. Promoting breast and cervical cancer screening among this currently underserved population may reduce future disparities.